DESCRIPTION (Investigator's abstract): The major focus of this research proposal is on the early processing and associated short-term storage of acoustic information. The mismatch negativity (MMN), an event-related potential (ERP) associated with sensory memory, will be the principal tool used in this endeavor. The proposed research will: (I) examine the manner in which information is stored in the memory; (2) evaluate reports that long term memory can facilitate the operation of sensory memory; (3) extend the finding that lip-read syllables can affect processing of concurrently spoken syllables in auditory cortex and thereby affect what is stored in sensory memory; (4) attempt to resolve a theoretical controversy concerning auditory regency effects by demonstrating that lip-read material (without accompanying sound) be entered into the memory; (5) inquire whether deaf subjects enter information acquired from lip-read and signed- speech signals into the memory; (6) examine in detail the scalp topography of auditory evoked potentials (AEP) and MMNs using scalp current density (SCD) mapping. The topographic mapping will define possible differential spatiotemporal patterns of the MNNs involved in the processing and storage of several aspects of auditory sensory information including frequency, intensity, duration, phonetic categorization and temporal patterning. These studies will test the hypothesis that the extent of cortical processing underling MMN generation differs for various stimulus features and for more complex comparisons involved in speech analysis and complex temporal sequences.